Cerebral hypoxia is a risk factor for death or severe neurologic complications (e.g., cerebral palsy) for low birth weight neonatal infants. Unfortunately, the ability of the cerebral vasculature of low birth weight neonates to maintain adequate cerebral blood flow is poorly understood. Although clinical studies have been performed with classical Kety-Schmidt methodology, Doppler ultrasound, positron emission tomography, perfusion computed tomography, magnetic resonance imaging and near-infrared (NIR) spectroscopy, there is currently no technique for easily, repeatedly and noninvasively monitoring or measuring cerebral circulatory adequacy in low birth weight infants. NIR spectroscopic techniques that rely on returning or transmitted light have limited ability to separate the signal derived from venous saturation, which reflects tissue oxygen uptake, and arterial saturation, which represents a component of oxygen supply. Moreover, the relative proportions of venous to arterial blood are altered by changes in body position, cerebral venous pressure (CVP), and cerebral vasodilatory stimuli.
In view of the above, it would be desirable to provide systems and methods for continuously monitoring cerebral oxygen in such patients. Ideally, such systems and methods can provide continuous monitoring of cerebral oxygen in the first 48 hours after birth, during which cerebral circulatory function must rapidly adapt to the change from the placental circulation to independent control of blood pressure. Evidence of cerebral ischemia can prompt therapy to increase cerebral blood flow.
References that may be of interest include: U.S. Pat. Nos. 4,537,197, 5,088,493, 5,099,842, 5,228,440, 5,348,002, 5,377,673, 5,823,952, 5,840,023, 5,941,821, 6,049,728, 6,381,480, 6,553,242, 6,594,515, 6,463,311, 6,466,806, 6,484,044, 6,567,678, 6,751,490, 6,846,288, 7,164,938, 7,322,972, 7,515,948, 7,747,301, 7,916,283, 8,121,663, 8,280,469, 8,332,006, 8,423,111, 8,501,099, 8,781,548, 8,852,095, 8,864,667, 8,885,155, 8,930,145, and 8,934,953; U.S. Publication Nos. 2006/100530, 2006/184042, 2007/015992, 2009/069652, 2009/108205, 2010/081904, 2011/239766, 2013/112001, 2013/190589, 2013/324815, 2014/142404, 2014/275943, 2014/343384, 2014/378811, 2015/051473, and 2015/099973; German Patent Publication No. DE 4400674 A1; and, “Noninvasive monitoring of cerebral blood oxygenation in ovine superior sagittal sinus with novel multi-wavelength optoacoustic system” to Petrov et al. (27 Apr. 2009/Vol. 17, No. 9/OPTICS EXPRESS 7285) and “Noninvasive optoacoustic monitoring of cerebral venous blood oxygenation in newborns” to Petrov et al. (Proc. SPIE 8223, Photons Plus Ultrasound: Imaging and Sensing 2012, 82231M (Feb. 9, 2012)).